I understand that the error above is nothing to do with ports or subdomains. I was simply pointing out that even if you take the trouble, and go through the process, of overcoming the initial issues of getting certbot to run on your Bitnami LAMP setup - it won’t issue you certificates for subdomains which only work on different ports ( not 80 or 443).
I am hopefully wrong, but I don’t believe that the “auto” function will work on your configuration, however with a little scripting you should be able to get something that works without you manually having to renew.